Faculty Research at Morehead State University


Dirk Grupe

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We present results of time-series analysis of the rst year of the Fairall 9 intensive disc-reverberation campaign. We used Swift and the Las Cumbres Observatory global telescope network to continuously monitor Fairall 9 from X-rays to near-infrared at a daily to sub-daily cadence. The cross-correlation function between bands provides ev- idence for a lag spectrum consistent with the / 43 scaling expected for an optically thick, geometrically thin blackbody accretion disc. Decomposing the ux into con- stant and variable components, the variable component's spectral energy distribution is slightly steeper than the standard accretion disc prediction. We nd evidence at the Balmer edge in both the lag and ux spectra for an additional bound-free continuum contribution that may arise from reprocessing in the broad-line region. The inferred driving light curve suggests two distinct components, a rapidly variable (< 4 days) component arising from X-ray reprocessing, and a more slowly varying (> 100 days) component with an opposite lag to the reverberation signal.



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